Larger Package Sizes

[xd4ps54]

I am trying to sell a poster which is larger than the dimensions of a medium parcel (61x46x46) but there is no option for any parcel larger. Am I simply not able to sell it? 

[**peaseblossom**]

The opt-out for large items (so you can use your own postage) is not working as it should at the moment but see the solution on here:
https://community.ebay.co.uk/t5/Seller-Central/how-do-you-list-anything-bigger-than-61cm/m-p/7882486...

@xd4ps54